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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 30-120 minutes
Siemens 8021 - Option 'activation of more than mode groups' not set
Alarm 8021 fires when the NCK attempts to activate a mode group that exceeds the licensed quantity defined in the machine's option package. The system detects a mismatch between the activated mode group count and the machine configuration parameter MD10200 (MaxModeGroups) or equivalent licensing restriction.
8021
Siemens 8021 - Option 'activation of more than mode groups' not set
Option 'activation of more than mode groups' not set
The option for the number of mode groups is not compatible with the activated mode group Control reaction: NC Start disable in this channel. Interface signals are set. Alarm display.
Root Cause Summary
Alarm 8021 fires when the NCK attempts to activate a mode group that exceeds the licensed quantity defined in the machine's option package. The system detects a mismatch between the activated mode group count and the machine configuration parameter MD10200 (MaxModeGroups) or equivalent licensing restriction.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Access Diagnostics > Parameters menu on the 840D control. Navigate to Machine Data (MD) and search for MD10200 (MaxModeGroups). Document the current value—this is the licensed maximum mode group count.
Do not modify MD10200 without authorization; this is option-protected data.
- 2
Check the active NC program or PLC logic for mode group selection commands (typically via M-codes or G-code modal groups). Verify the highest mode group number being referenced does not exceed the MD10200 value.
- 3
If the program legitimately requires additional mode groups, contact Siemens licensing to upgrade the machine option package. Request an option key update and reload it via Startup > Service > Licensing.
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